Question

Native americans were massacred at this site in the 1800's and it became the location of a tense standoff in the modern native american rights movement.

Answer 1

I think maybe the answet you are looking for is wounded knee. There was a massacre there in 1890 and then in 1973 multiple members of the Antive american movement occupied the site for more than 70 days to protest the condition of reservation and the treatment of native americans.